Vacuum pump



`Iam. 14, 1964 G. ZIPPE ETAL 3,117,713

VACUUM PUMP Filed Nov. 24, 1958 United States Patent C) 3,117,713 VACUUM PUMP Gernot Zippe, Charlottesville, Va., Rudolf Schelel, Frankfurt am Main Romerstadt, and Max Steenbeek, Hilgenfeldvveg 6, Jena, Germany; said Zippe and said Scheffel assignors to Deutsche Goidund SilberSeheideanstalt vormals Roessler, Frankfurt am Main, Germany Fired Nov. 24, 195s, ser. No. 845,585 Claims priority, application Austria Nov. 28, 1957 (Filed under Rule 47(a) and 35 U.S.C. 116) 2 Claims. (Cl. 230-45) The invention relates to an apparatus for producing and maintaining a pressure diierence between two connected spaces containing a gaseous medium, and more particularly to a vacuum pump or molecular packing.

For this purpose, steam jet pumps, molecular air pumps and the like have been previously used.

The primary object of the invention is to provide an improved device operating in a new and more eiicient manner to accomplish this result.

Another object of the invention is to provide a simple, light and inexpensive construction of such a device.

According to the invention, the device includes a stator and at least one rotor with a high peripheral speed, one of these elements being provided with spiral grooves in one of its walls facing a wall of the other element, With such an arrangement it is possible, with low power consumption, to maintain a pressure difference between the gas in two spaces or areas, so as in effect to seal them off from each other, or to produce a pressure diiference so as to pump gas from one area to the other. It is possible to maintain in this way a high ratio of pressure between two areas; for example, with heavy gas a ratio of 1:1000 or more can be attained.

Preferably, the work of pumping is divided between two stages, one having a lower peripheral speed and operating at a higher pressure and the other having a higher peripheral speed and operating at a lower pressure. Because the higher pressure is in this case screened off from the faster moving part of the rotor, friction losses are reduced.

Preferably also the rotor is hollow and the gas outlet includes pipes located inside the rotor and having inlet openings spaced from the rotor axis and facing opposite to the direction of rotation of the rotor. Thus the kinetic pressure of the moving gas is used to assist in the removal of the gas from the rotor, so that by suitable proportioning of the cross section and length of the outlet passage the rate of removal can be adjusted.

Further objects and advantages of the invention will appear more fully from the following description, especially when taken in conjunction with the accompanying drawing, which form a part thereof.

In the drawing:

FlG. l is a vertical cross-section through the apparatus substantially on the line 1-1 of FIG. 2; and

FIG. 2 is a cross-section on the line 2 2 of FIG. 1.

In the drawing, 1 indicates the high pressure area, that is, the space to which air is to be driven, this area being shown as occupying a part of a stator casing 1a having an outlet 1b. A space 2 forming an intermediate chamber is shut olf from area 1 by Wall 4. The low pressure area is indicated at 3 with an inlet 3a.

Wall 4 has a downwardly extending annular projec- ICC tion 6 having an open passage 5 therethrough, the outside of this projection forming a wall section which faces the inner wall of an upward projection 9 of the hollow rotor body 8. At least one of this pair of wall sections, such as the stator section, has spiral grooves 7 therein, these grooves being close to but slightly spaced from the other wall section. Rotor S is mounted to tum in any suitable manner about axis 8'. It may, for instance, be mounted in bearing Sa held in the stator by braces 8b, and driven at a high speed, such as to have a peripheral speed of 330 meters per second or more, by motor 8c through belt 8d.

The stator also includes a cylindrical body 10 having its inner wall facing the outer wall of the main body of rotor 8. At least one of this pair of wall sections, such as the stator section 10, has spiral grooves 11 therein. The wall sections 8, lil are further from the axis S' than sections 6, 9 and therefore move with a greater peripheral speed, but all the wall sections are concentric with the axis.

At the bottom of tubular projection 6 are transverse pipes 12, having their ends bent as at 13 and having openings 14 facing in a direction opposite the direction 0f rotation of the rotor.

The pair of wall sections 8, 10 draws gas from space 3 either to maintain a vacuum in that space or to pump gas from some area connected to pipe 3a. This gas passes through the space between the wall sections into intermediate chamber 2, from which it is drawn by wall sections 6, 9 into the hollow space inside the rotor. The pair 8, 10 then operates at a higher peripheral speed, but with a lower pressure, than the pair 6, 9.

This arrangement is useful for high speed contrifuges, in which a separation of heavy components of gases takes place within the rotor. It is also useful as a vacuum pump, especially for heavy gases.

While we have described herein some embodiments of our invention, we wish it to be understood that we do not intend to limit ourselves thereby except within the scope of the claims hereto or hereinafter appended.

We claim:

1. Apparatus for producing and maintaining a pressure diiference between two gas-containing spaces, comprising a stator and a hollow rotor having a cylindrical wall section enclosed in and mounted to rotate with respect to the stator, the stator having a wall facing said cylindrical Wall section, the rotor also having an opening in its top with a tubular section around the opening concentric with and of less diameter than the cylindrical wall section of the rotor, the stator having a tubular section concentric with and closely adjacent the rotor tubular section, such stator tubular section being inside the rotor tubular section, at least one of said tubular sections having spiral grooves therein in the wall facing the other tubular section, and means to rotate the rotor at high speed, the stator having a low pressure area and an intermediate chamber therein, the space between the cylindrical wall section of the rotor facing wall of the stator communicating at one end with said low pressure area and at the other end with said intermediate chamber, said rotor having a closed hollow space therein, the space between the pair of tubular sections communicating at one end with said intermediate chamber and at the References Cited in the iile of this patent UNITED STATES PATENTS Coats Apr. Meldahl Nov. Van Dorsten et al. Jan. Audemar Oct.

FOREIGN PATENTS Great Britain Sept. Great Britain Sept. 

1. APPARATUS FOR PRODUCING AND MAINTAINING A PRESSURE DIFFERENCE BETWEEN TWO GAS-CONTAINING SPACES, COMPRISING A STATOR AND A HOLLOW ROTOR HAVING A CYLINDRICAL WALL SECTION ENCLOSED IN AND MOUNTED TO ROTATE WITH RESPECT TO THE STATOR, THE STATOR HAVING A WALL FACING SAID CYLINDRICAL WALL SECTION, THE ROTOR ALSO HAVING AN OPENING IN ITS TOP WITH A TUBULAR SECTION AROUND THE OPENING CONCENTRIC WITH AND OF LESS DIAMETER THAN THE CYLINDRICAL WALL SECTION OF THE ROTOR, THE STATOR HAVING A TUBULAR SECTION CONCENTRIC WITH AND CLOSELY ADJACENT THE ROTOR TUBULAR SECTION, SUCH STATOR TUBULAR SECTION BEING INSIDE THE ROTOR TUBULAR SECTION, AT LEAST ONE OF SAID TUBULAR SECTIONS HAVING SPIRAL GROOVES THEREIN IN THE WALL FACING THE OTHER TUBULAR SECTION, AND MEANS TO ROTATE THE ROTOR AT HIGH SPEED, THE STATOR HAVING A LOW PRESSURE AREA AND AN INTERMEDIATE CHAMBER THEREIN, THE SPACE BETWEEN THE CYLINDRICAL WALL SECTION OF THE ROTOR FACING WALL OF THE STATOR COMMUNICATING AT ONE END WITH SAID LOW PRESSURE AREA AND AT THE OTHER END WITH SAID INTERMEDIATE CHAMBER, SAID ROTOR HAVING A CLOSED HOLLOW SPACE THEREIN, THE SPACE BETWEEN THE PAIR OF TUBULAR SECTIONS COMMUNICATING AT ONE END WITH SAID INTERMEDIATE CHAMBER AND AT THE OTHER END WITH SAID HOLLOW SPACE, SAID STATOR HAVING A PASSAGE THEREIN FOR THE ESCAPE OF GAS, SAID PASSAGE INCLUDING PIPES IN SAID HOLLOW SPACE TRANSVERSE TO THE AXIS OF THE ROTOR AND HAVING INLET OPENINGS THEREIN FACING IN A DIRECTION OPPOSITE THE DIRECTION OF ROTATION OF THE ROTOR. 